1. Field of the Invention
This invention relates to a grinder assembly and more particularly to a grinder assembly having adjustment means for grinding the circular edge of a pipe.
2. Description of the Prior Art
The gas transmission lines spanning the country are assembled by welding sections of relatively large diameter pipe to form the continuous pipe line. The pipe sections are cut and brought to the job site and frequently are cut at the job site. In cutting the pipe sections, frequently the cutting results in a pipe section that has an edge portion cut at an angle other than perpendicular to the longitudinal axis of the pipe or stated otherwise the end portion of a pipe is nonperpendicular to the longitudinal axis of the pipe section. Also during the cutting operation, frequently the edge of the pipe is not linear in that it has slightly curved or undulating portions. In storage of the pipe sections at the job site and/or transporting them to the job site, the pipe sections are stacked on top of each other and because of the weight certain of the sections are distorted and not perfectly round so that they take on a slight elliptical configuration.
Before the pipe sections are welded to each other, the edges of the pipe are beveled to form a V-shaped groove and the edges also preferably have a flat land portion. The end sections of the pipe are also ground to remove the rust and cleanse the pipe so that a gas tight weld can be made between the sections.
Because of the distorted edges of the pipe sections, presently substantially all of the grinding is done manually to form the V-shaped grooves and lands. This is an expensive and time consuming operation. There is a need for an automated device for grinding the edges of the pipe sections which is adjustable to compensate for the imperfections in the pipe edge sections during the grinding operation.
The prior art discloses abrading machines or grinding machines for grinding pipe flanges, railway journal boxes and ends of pipe sections. For example, U.S. Pat. No. 2,801,506 discloses a jig for grinding journal box surfaces and includes a means to adjust the grinding wheel radially from a guide post. U.S. Pat. No. 2,736,995 discloses a pipe flange grinding machine that also has the grinding wheel adjustable in a radial manner. The assembly is mounted on the pipe flange and secured within the inner portion of the pipe by a support device.
U S. Pat. No. 1,031,934 discloses a grinding machine that is supported within a pipe section by a support means and has a motor driven grinder mounted on a turntable, and a motor mount is adjustable radially.
U.S Pat. No. 2,869,293 discloses a mounting for a pipe end grinder where the grinder is supported by a support means secured within the pipe and has a grinding wheel that is angularly adjustable to the longitudinal axis of the pipe and has a resilient means to urge the grinding wheel against the edge of the pipe.
U.S. Pat. No. 2,188,720 discloses an abrading machine that is supported within the pipe and has grinding wheel mounted thereon that appears to be adjustable radially relative to the longitudinal axis of the pipe.
U.S. Pat. No. 2,587,398 discloses an annular grinding or abrading device that is mounted on a support secured within the pipe section. The annular grinding wheel extends around the periphery of the pipe and is urged against the edge portion and manually rotated to perform the finishing of the pipe edge.
U.S. Pat. No. 2,414,731 discloses a grinding attachment for grinding the end face of a pipe and includes a three leg support within the pipe for the grinder. The grinder has a shaft portion that extends into an axial tube of the support device and is rotatable about the periphery of the pipe edge. In one embodiment, the grinding wheel is adjustable to change the angle of a grinding wheel surface relative to the edge of the pipe to form a bevel thereon.
Although some of the above prior art disclose grinder assemblies for grinding the edge of a pipe, there is a need for a grinder assembly that not only supports the grinder for rotation around the periphery of the pipe edge portion but also for a grinding assembly where the face of the grinder wheel can be adjusted to compensate for pipe edge portions that are cut at an angle other than an exact perpendicular to the longitudinal axis of the pipe and also adjustment means to adjust the grinding wheel for uneven portions of the pipe edge.